Apparatus for depositing a magnetic thin film on a substrate by depositing material sputtered from a target consisting of a film forming bulk material is known. Sputtering of the material should be carried out while applying a parallel magnetic field so that the magnetic domains in the films being formed can be oriented in the same direction.
In this case, there are two kinds of methods using permanent magnets or magnetic field coils as means for generating the parallel magnetic field. The method of the magnetic field coils is better compared with the method of the permanent magnets because the magnetic field characteristic thereof does not cause deteriorate with time and it is adjustable.
However, the method of the magnetic field coils has a drawback in that it is difficult to apply a magnetic field which is uniform and parallel to the entire substrate surface.
For resolving the drawback, a sputtering apparatus for production of thin films of magnetic materials was proposed which adjusts the magnetic field applied to the substrate using a magnetic plate as shown in, for instance, FIG. 1 of Japanese Patent Laid-Open No. 57-78123 published on May 15, 1982 and entitled "Manufacturing Method of Different Direction magnetic Thin Film".
In general, sputtering apparatus for production of thin films of magnetic materials comprises a target consisting of a film forming bulk material, a magnetic film deposition chamber which is provided with a magnetic field generating apparatus, and a preliminary chamber which is connected to the magnetic film deposition chamber through a gate valve which opens and closes.
Usually, a number of preliminary chambers are connected to the magnetic film deposition chamber through gate valves provided between the preliminary chambers and the magnetic film deposition chamber. In each preliminary chamber, all kinds of preliminary treatment such as preliminary heating, gradual cooling, abrupt cooling, intake, and offtake, are performed on magnetic field deposition by closing the gate valve.
The substrate, which receives the predetermined preliminary treatment within the preliminary chamber while being held on a substrate holder, is conveyed to the magnetic film deposition chamber through the opened gate valve by means of a conveyor of the substrate holder.
In the magnetic film deposit chamber, a magnetic field, having a predetermined direction generated by a magnetic field generating apparatus, is applied to the surface of the substrate. The bulk material is sputtered from the target to the surface of the substrate while the magnetic field is applied, so that the magnetic material is deposited on the surface of the substrate.
FIG. 1 shows a main section view of the magnetic film deposition chamber of the sputtering apparatus for production of thin films of magnetic material according to the device disclosed in FIG. 1 of the above-mentioned Japanese Patent Laid-Open No 57-78123. In the magnetic film deposition chamber, a target 10 consisting of a film forming bulk material is provided. An electrical lead 9 is fixed to the target. A pain of Helmholtz coils 3 are arranged within the magnetic film deposition chamber. The substrates 5 mounted on the substrate holder 4 are conveyed by the conveying means 8 from the preliminary chamber to the position shown between the pair of Helmholtz coils 3, and are located above the target 10. Apertures 15 are formed in the substrate holder 4. The substrates 5 are held on the substrate holder 4 conveying the apertures 15. The substrates 5 are located between a pair of magnetic plates 6 mounted on the substrate holder 4. The magnetic plates 6 mounted on the substrate holder 4 are fixed near the both ends of the substrate holder 4, respectively, along the longitudinal direction of the substrate holder 4, and are made from the same magnetic material as the target 10. The substrate holder 4 is conveyed from the preliminary chamber to the magnetic field deposition chamber through a gate valve such that the substrate holder 4 holds the substrate 5 and the magnetic plates 6.
In the apparatus disclosed in FIG. 1, at first, the gate valve between the preliminary chamber and the magnetic film deposition chamber is closed. Next, the substrates 5 are arranged between the magnetic plates 6 fixed to the substrate holder 4 at the preliminary chamber, and it is subjected to a predetermined treatment with the preliminary chamber.
After the preliminary treatment has taken place in the preliminary chamber, the substrate holder 4, which fixes the magnetic plates 6 thereon and holds the substrates 5 between the magnetic plates 6, is conveyed from the preliminary chamber to the magnetic film deposition chamber through the opened gate valve by the conveying means 8.
Next, the gate valve between the preliminary chamber and the magnetic film deposition chamber is closed, and then the surface of the substrate 5 is disposed by the bulk magnetic material 6, for instance permalloy, thus the magnetic field is applied parallel to the surface of the substrates 5 by the magnetic field generating apparatus and the bulk material is sputtered from the target 10 the surfaces of the substrates through the apertures 15 in an atmosphere of argon gas.
The magnetic material sputtered from the target 10 reaches the surfaces of the substrates 5, and forms a magnetic film which is magnetized in the same direction.
In the system explained above, since the magnetic plates 6 comprising, for instance, permalloy, dispose the substrates 5 between a pain of Helmholtz coils, the magnetic field generated by the magnetic field generating apparatus, as shown by arrow H in FIG. 1, whose main element comprises the Helmholtz coils 3, is concentrated by the magnetic plates 6 so that the magnetic field becomes parallel to the surfaces of the substrates 5 and the magnetic flux density is adjusted uniformly.
Ordinarily, a number of substrates 5 are held on the common substrate holder 4 for increasing the manufacturing performance of the magnetic films produced on the surfaces of the substrates shown in FIGS. 1 and 2, and the magnetic films are deposited on a number of the substrates at the same time.
According to the prior art, the magnetic field, which is generated by the magnetic field generating apparatus comprising the Helmholtz coils 3 as the main element, is adjusted by the magnetic plates 6 which are fixed on the substrate holder 4, and it becomes parallel to the substrate surfaces, with a uniform, high magnetic flux density, so that the apparatus of the prior art can manufacture high quality films on the substrates 5.
Since the magnetic plates 6 of the prior art are fixed on the substrate holder 4, the substrate holder 4 becomes large in size, and the large size substrate holder 4 has to be conveyed by the carrying means from the preliminary chamber to the magnetic film deposition chamber through the gate valve.
Accordingly, the preliminary chamber of the prior art requires a large space as will as the magnetic film deposition chamber for accommodating the large size substrate holder 4. The apparatus of the prior art thus has the drawback that the size thereof becomes large.